This invention relates generally to machine control. In particular this invention relates to coordinated motion of a tool carried by a program controlled manipulator with motion of a workpiece carried by a program controlled positioner.
Some applications of program control manipulators require, in addition to the motion imparted to the tool carried by the manipulator, that the workpiece be rotated to provide continuous processing over surface segments which cannot simultaneously be presented in the most advantageous attitude. For example, where seam joining or sealing is involved, best results are achieved when gravity assists the deposition of material. However, where the seam traverses a contour on a curved plane or across multiple flat planes, it is not always possible to achieve a suitable relative orientation of workpiece and tool without rotating the workpiece. The coordination of tool motion and workpiece motion presents difficulties in program creation as the effective relative velocity of workpiece and tool may vary with position as the desired relative motions are executed. In some previously known control systems, all motions of the manipulator were affected if there was a simultaneous motion of the workpiece, even if the combined motions were not being executed to perform work on the workpiece. Thus, prepositioning moves from a rest or load location to a process start location would be affected by the motion coordinating algorithms.
Further, in previously known systems, program creation required that the programmer enter the effective path distance resulting from the combined motions. As manipulator programs have traditionally been created by a process of manually commanded positioning and data recording, the span length computation required for coordinated motion conflicts with the traditional program creation process.
It is, therefore, one object of the present invention to provide a manipulator control for coordinating motion of a manipulator with rotation of a workpiece in response to input signals defining the beginning and end points of motions of both the manipulator and the workpiece positioner and the relative velocity between a tool carried by the manipulator and the workpiece surface.
It is a further object of the present invention to provide a control for a program controlled manipulator for coordinating linear motions effected by the manipulator with workpiece rotations when these simultaneous motions are initiated within a predefined envelope describing proximity of a tool centerpoint to the workpiece positioner.
It is a still further object of the present invention to provide a control for a program controlled manipulator for coordinating the linear motion effected by the manipulator with workpiece rotation where the radius of the workpiece changes within the span length traversed by the tool centerpoint.
It is a still further object of the present invention to provide a control for a program controlled manipulator for coordinating the linear motion effected by the manipulator and workpiece rotation wherein the effective relative motion of the tool centerpoint to the workpiece surface includes a substantial tangential component.
Further objects and advantageous of the present invention shall become apparent from the appended drawings and the description thereof.